Remove arbitrary timeout in unit test support. This was causing flakiness...

Remove arbitrary timeout in unit test support. This was causing flakiness during builds if the machine is loaded. (changeset 1397093)

src/Compilers/Core/VBCSCompilerTests/CompilerServerApiTest.cs

@@ -137,7 +137,7 @@ private async Task<BuildResponse> RunCSharpCompile(string pipeName, string sourc
             using (var namedPipe = new NamedPipeClientStream(".", pipeName, PipeDirection.InOut))
             {
                 var buildRequest = await CreateBuildRequest(sourceText, keepAlive).ConfigureAwait(false);
-                namedPipe.Connect((int)TimeSpan.FromSeconds(5).TotalMilliseconds);
+                namedPipe.Connect(Timeout.Infinite);
                 await buildRequest.WriteAsync(namedPipe, default(CancellationToken)).ConfigureAwait(false);
                 return await BuildResponse.ReadAsync(namedPipe, default(CancellationToken)).ConfigureAwait(false);
             }